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BUG: KCSAN: data-race in ext4_mb_scan_group / mb_free_blocks

read-write to 0xffff888100478014 of 4 bytes by task 2964 on cpu 0:
 mb_free_blocks+0x402/0xbc0 fs/ext4/mballoc.c:2042
 ext4_free_data_in_buddy fs/ext4/mballoc.c:3986 [inline]
 ext4_process_freed_data+0x301/0x6a0 fs/ext4/mballoc.c:4022
 ext4_journal_commit_callback+0x65/0x3a0 fs/ext4/super.c:514
 jbd2_journal_commit_transaction+0x2b17/0x33d0 fs/jbd2/commit.c:1121
 kjournald2+0x22e/0x3e0 fs/jbd2/journal.c:201
 kthread+0x488/0x510 kernel/kthread.c:463
 ret_from_fork+0x148/0x280 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

read to 0xffff888100478014 of 4 bytes by task 19564 on cpu 1:
 ext4_mb_good_group_nolock fs/ext4/mballoc.c:2779 [inline]
 ext4_mb_scan_group+0x470/0xf20 fs/ext4/mballoc.c:2954
 ext4_mb_scan_groups_linear fs/ext4/mballoc.c:1163 [inline]
 ext4_mb_scan_groups fs/ext4/mballoc.c:1197 [inline]
 ext4_mb_regular_allocator+0x738/0x1610 fs/ext4/mballoc.c:3046
 ext4_mb_new_blocks+0x809/0x2080 fs/ext4/mballoc.c:6317
 ext4_ext_map_blocks+0x106d/0x38a0 fs/ext4/extents.c:4383
 ext4_map_create_blocks fs/ext4/inode.c:613 [inline]
 ext4_map_blocks+0x65e/0xd70 fs/ext4/inode.c:816
 ext4_getblk+0x128/0x530 fs/ext4/inode.c:984
 ext4_bread+0x28/0x110 fs/ext4/inode.c:1047
 ext4_append+0x181/0x2c0 fs/ext4/namei.c:83
 ext4_init_new_dir+0xec/0x180 fs/ext4/namei.c:2979
 ext4_mkdir+0x31e/0x740 fs/ext4/namei.c:3015
 vfs_mkdir+0x510/0x560 fs/namei.c:5139
 do_mkdirat+0x133/0x3b0 fs/namei.c:5173
 __do_sys_mkdirat fs/namei.c:5195 [inline]
 __se_sys_mkdirat fs/namei.c:5193 [inline]
 __x64_sys_mkdirat+0x4c/0x60 fs/namei.c:5193
 x64_sys_call+0x30c/0x3000 arch/x86/include/generated/asm/syscalls_64.h:259
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000074c -> 0x00000752

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 19564 Comm: syz-executor.5 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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/dev/loop5: Can't open blockdev